Influence of Load on the Magnitude of the Life Exponent for Rolling Bearings

Extensive realistic tests to determine rolling bearing life have previously indicated that the exponent p in the well-known formula Ln = (C/P)p is a constant, and various institutes of technology have agreed that for ball bearings in particular this constant p = 3. Acceptance of this constant means that even under low load conditions a finite life is always to be expected at rolling contact surfaces. However, the classic theory of the strength of materials states that metals, especially steel, have a virtually unlimited life under a cycling load below a defined level. Recent tests on rolling bearings confirmed that under low loads and with elastohydrodynamic lubrication there is no material fatigue, thus indicating that under such conditions bearing life is practically unlimited. The recent tests further indicate that surface damage caused by particles entering a rolling bearing is a much more important factor in limiting bearing life than had previously been believed.